Manually activated pre-filled cartridges are commercially available from a variety of manufacturers, including the owner and assignee of the present invention. Pre-filled cartridges are used in the administration of drug solutions, drug suspensions, vaccines, medicinal therapies, and any other liquid medicament by parenteral injection. Such pre-filled cartridges include a primary drug chamber, a hypodermic needle permanently affixed to and in fluid communication with the drug chamber, and a piston slidably received in the drug chamber. The pistons of the pre-filled cartridges often include a plunger sub-assembly, which may include a plunger inner and a plunger outer, to force the liquid medicament from the needle. Pre-filled cartridges are typically prepared by pharmaceutical companies or sterile filling contractors in a sterile filling room in which the drug and the cartridge are brought together in a sterile manufacturing environment wherein all components and drug solutions are isolated from microbial contamination. Currently, visual, tactile or audible indicators are generally linked to the end of stroke or some other mechanical mechanism and not to the end of dose. The integrated needle retraction syringe retracts the needle into the barrel, removing it from the patient's skin, once the dose is complete.
In contrast to manually activated pre-filled cartridges, automatic injection devices, commonly known as “auto injectors,” are also available. Such auto injectors, once triggered by the user, use an automatic mechanism to insert a hypodermic needle into the recipient's flesh at the injection site and force the liquid medicament out of a medicine compartment, through the hypodermic needle, and into the recipient. In addition, some auto injectors also incorporate retraction mechanisms to automatically retract the needle after use. Auto injectors have proven particularly useful in allowing the medically untrained user to administer a parenteral injection, and can provide both psychological and physical advantages to patients.
Patients needing to inject medication for chronic disease management have used auto injectors since the first reusable auto injector was introduced in the 1990s. An auto injector provides protection for the primary container, generally a pre-filled syringe, and offers an easy way for administration of medication. These devices offer increased convenience and autonomy for patients as well as providing a competitive advantage to the pharmaceutical partner through device differentiation and increased sales by facilitating compliance of the patient to their therapy. Auto injectors may also be beneficial in delivering large volumes (up to 1 mL currently) and viscous drugs. Auto injectors also work to prevent needle stick injuries by housing the needle within a chamber, inserting the needle into the patient for drug introduction, then retracting the needle back into the housing utilizing, for example, reverse drive mechanisms.
Moreover, some auto injectors have been designed to accept commercially available, manually activated cartridges. Such configurations may be made in the form of cartridges for auto injectors (e.g., reusable auto injectors) or single-use auto injectors. The syringes developed and manufactured by the owner and assignee of the present invention offer unique and elegant integrated retraction mechanism for needle safety. A number of different syringes and cartridge configurations may be utilized in such auto injectors, including those sold by under the trade names “Unifill” and “Unifill Finesse” and covered by one or more of the following: U.S. Pat. Nos. 6,083,199, 7,500,967, 7,935,087, 8,021,333, 8,002,745, 8,052,654, 8,114,050, and 8,167,937; U.S. Patent Pub. No. 2011/0015572 and U.S. Patent Pub. No. 2013/0226084; and International PCT App. Nos. PCT/AU2010/001505, PCT/AU2010/001677, PCT/AU2011/000515, PCT/US2012/067793, and PCT/US2014/024781 all of which are incorporated herein by reference, in their entirety, for all purposes. The automatic injectors are also designed to accept a variety of syringes as filled drug-container cartridges, i.e., as pre-filled syringes, including the “Unifill” and “Unifill Finesse” syringes described herein.
Placement or orientation of the auto injector device relative to the injection site is critical for successful outcome of the drug delivery. For example, a patient may be required to place the auto injector device on the injection site so that the device remains perpendicular throughout the drug delivery process. However, stringent positional requirements of such a device may pose challenges for some patients. Particularly, due to a lapse in concentration or due to lack of dexterity, older patients may substantially tilt the auto injector device, and improperly inject the wrong tissue. This may lead to erroneous treatment, which consequently could be detrimental to the health of the patient.
To-date, auto injector devices do not provide continuous guidance associated with the positioning of the device. As a result, due to lack of assistance from the device, it may be difficult for the patient to maintain the required position or orientation of the auto injector, and the patient may improperly place the auto injector during the drug delivery period.
Therefore, there is a need for improved auto injector devices that are operable only when the devices are in contact with and/or are properly oriented with respect to the patient's skin during the drug delivery process.